Tip:
Highlight text to annotate it
X
My name is Jim Butler. I’m the director of the Global Monitoring Division of NOAA’s Earth System Research Laboratory.
The Annual Greenhouse gas index is a measure of the climate warming influence of a suite of greenhouse gases that we measure in the atmosphere routinely over decades.
These gases are at very low concentrations, some of them, others are at just low concentrations.
They’re composed primarily of carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, other gases.
Mainly CO2 [carbon dioxide] is driving the annual greenhouse gas index increase that we see today.
Humans for the last few centuries have been pouring greenhouse gases into the atmosphere
and we have been monitoring this very, very tightly at hundreds of sites over the last 50 years, but we are able to draw records, actually about the last 60 years.
But we are able to draw records going back through snow and ice records back through 800,000 years.
We can see that what we are doing today is a very strange thing in the history of the last million years
I like comparing the AGGI to the dial on an electric blanket.
You turn the dial up and you know you’re going to get warmer, but you don’t know how much warmer you’re going to get.
You can estimate how much warmer it’s going to get. But you turn it up and at first you don’t feel much…
then you might stop turning it up and you feel warmer, but what if you find out you can’t turn it down? This is the AGGI.
This animation of NOAA and other data shows how levels of carbon dioxide in the atmosphere have changed over time.
Carbon dioxide is the most important greenhouse gas and a key part of NOAA’s Annual Greenhouse Gas Index.
The first thing to note here, between 1950 and the present, is the wiggling up and down of global carbon dioxide levels.
That’s from natural seasonal cycles dominated by a land-rich northern hemisphere.
The fact that the wiggly line rises steadily upward, however, is because of steady emissions of greenhouse gases into the atmosphere by human activities.
Once we go back to before the 1950s, we turn to bubbles trapped in old ice layers and snow for information about the composition of the atmosphere
You can see various cycles up and down as we go farther into the past
mostly caused by wobbles in Earth’s orbit at a time scale of about 100,000 years.
What’s important here is that in records that reach back 800,000 years
we have never seen carbon dioxide levels anywhere near what they are today, more than 390 ppm.
In fact, it’s only in the last 100 years that we’ve seen CO2 exceed 290 ppm.
In fact, it’s only in the last 100 years that we’ve seen CO2 exceed 290 ppm.
NOAA’s mission is to understand and predict changes in Earth’s environment.
By measuring these gases in the atmosphere, on a regular basis, getting the highest quality measurements we can,
we can understand where we’ve been, but we can also get an idea of where we’re going.